


Side Effects

by torino10154



Category: Harry Potter - J. K. Rowling
Genre: Anal Sex, M/M, Potions-induced consent, Teacher-Student Relationship, Underage Sex
Language: English
Status: Completed
Published: 2011-11-09
Updated: 2011-11-09
Packaged: 2017-10-25 21:34:05
Rating: Explicit
Warnings: Underage
Chapters: 1
Words: 1,368
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/275025
Author URL: https://archiveofourown.org/users/torino10154/pseuds/torino10154





	Side Effects

**Title:** Side Effects  
 **Prompt #** 93\. Prompt: Neville has to skip the Halloween feast because Professor Snape assigned him detention, where he must brew a potion that he messed up in class. He messes up again, of course, but this time the potion has some rather interesting effects on both of them.  
 **Pairing(s)/Character(s):** Snape/Neville  
 **Rating:** NC-17  
 **Summary** See prompt.  
 **Word Count:** ~1245  
 **Warnings/Content:** Anal, potion induced consent for both, slightly AU in that Neville is still taking Potions 6th year, which also means he's 16.  
 **Disclaimer:** The characters named herein belong to JKR.  
 **Author's notes:** Thank you to my betas, Demicus and Jadzialove, for their help. Any mistakes that remain are mine alone. I modified the prompt slightly.

Neville knocked on the door to the Potions classroom at precisely eight o'clock. Hopefully he'd manage to make the Prophylactic Pumpkin Pomade correctly the first time and he could get back to the Halloween feast in time for pudding.

"Enter." Neville's heart jumped into his throat. That was not Professor Slughorn. He opened the door slowly, hoping against hope that he'd just imagined the deep voice that had given him nightmares for years. However, sitting behind the teacher's desk was Professor Snape.

"Professor?" he said, clearly his voice when it cracked slightly. "I—I was expecting Professor Slughorn."

"Professor Slughorn cares more for drink than Potions," Snape snapped and flicked his wand at the chalkboard without looking up, the directions for the pomade appearing in his distinctive spiky handwriting.

Neville blinked. He wasn't very good at Potions, but he was quite sure these instructions were different than the ones in his copy of _Advanced Potion Making_. This called for ginger and cloves, as well as a fair amount of gelatinous Flobberworm innards. Revolting.

"Get started, Longbottom." Snape went back to marking what must presumably be Defence essays unless Slughorn had Snape marking Potions essays as well. Neville swallowed. He had hoped to at least earn an Acceptable in the class in order to continue toward a Masters in Herbology someday.

Neville gathered the necessary items from the ingredient cupboard and set them down beside the copper cauldron and glass stirring rod. He began chopping Flobberworms after he'd lit the fire. Without the other students distracting him, he found he wasn't so easily flummoxed.

He hummed happily as he worked, the pumpkin from Hagrid's patch giving the slick unguent an orange tint. Stirring in lazy figure eights, Neville began to feel warm, his vision blurring slightly. He thought that was odd, but it didn't seem worth worrying about. He was somehow too relaxed to care….

"Longbottom!" he heard, although the voice sounded very far away. He looked up and saw Professor Snape's eyes widen as he looked at Neville and then back at the chalkboard.

Neville could tell the moment Professor Snape succumbed to the same feeling of lassitude that Neville was currently experiencing. His eyes were lidded as he moved slowly toward Neville, unbuttoning the top button of his robes. Neville suddenly thought that was the best idea Snape had ever had and began removing his own robes.

By the time Snape had reached him, Neville had slipped out of his robe and was unbuttoning his shirt. Snape reached out and gripped his hand, eyes burning with more fire than Neville had ever seen in them.

"What did you _do_?" Snape said through clenched teeth even as his robes fell to the floor.

"Just what it says on the board, Professor." Neville leaned in and inhaled. Since when had Snape smelled so _edible_?

Snape's hands pushed Neville's out of the way, pushing his shirt off his shoulders. "You added Chinese chamomile rather than Chinese Chomping Cabbage." He rubbed one of Neville's nipples with his thumb and Neville groaned. "That is why you feel so relaxed."

"Good to know, Professor." Neville's hips rolled forward hoping to come into contact with something, anything at this point, but Snape was still too far away. Neville reached into his pants and hissed as he wrapped his hand around his cock. "Yessss."

"Do you know why you are aroused, Longbottom? What foolish mistake you made that has drawn us together?" Snape asked, even as he too had undone his flies and was stroking his—his _magnificent_ cock. Neville's mouth watered just looking at it.

When he finally drew his eyes away, black ones burned him with their intensity. "Well?"

Neville tried to remember the question but it was impossible, not with Snape stroking his cock less than a foot away. "I have no idea, Professor."

Snape moaned, eyes fluttering closed for a moment, before opening them again, hungrier than before. "Neither do I. You are a singularly amazing individual, Longbottom. Making errors even I cannot fathom."

Neville leaned forward, pressing his face to Snape's neck, inhaling the scent once more. "You smell good," he said softly, unconcerned he was _sniffing_ Professor Snape.

"Trousers off, Longbottom," Snape said and held out his hand. A phial flew into it and Snape immediately poured some of the liquid into his other hand and began rubbing it over the length of his cock.

Even as Neville pushed his trousers and pants down, his cock springing free of its confines, he asked, "What's that?"

"Lubrication." Snape didn't explain further only added, "Bend over and grasp your ankles."

It was somehow the best idea Neville had ever heard in his life and he hastened to obey. The first touch of warmth to his arse shocked him, but it was immediately replaced by pleasure as the unguent cleaned, loosened, and warmed his delicate flesh, Snape's two fingers doing their share of the work inside him.

"Hurry, Professor, please," he said, blood rushing to his head, his desire to be filled making his knees tremble.

He could see when Snape stepped closer widening his stance as he pressed the head of his cock to Neville's eager hole.

"Oh, oh, oh," Neville gasped, never having felt anything like this before. Nothing like his fingers, Snape's cock was thick and smooth, sliding in inch by inch, giving Neville the chance to breathe through the burn.

Snape's hands settled on his hips when he was fully seated. "Exquisite," Neville thought he heard, but then Snape began to thrust and Neville saw stars. His cock was leaking copious amounts of precome and he knew if he could touch it, he'd come immediately.

Instead he just allowed himself to be used, a hole for Snape to fuck, a certain thrill in knowing it was hated Professor Snape that was moaning behind him.

Snape's fingers dug into his skin as he began moving faster and Neville knew he was getting close.

"Fuck me, Professor," he said, inspired. "Fuck me harder."

Snape growled and slammed into him, pulsing his release into Neville's arse. After a moment, he slowly pulled out and Neville winced slightly.

"Make yourself come, Longbottom," Snape said and Neville stood, his back aching and feeling a bit lightheaded. He turned to face Snape, though, and wrapped his fist around his painfully hard cock.

He looked Snape in the eye and wanked himself three times before his bollocks drew up and he cried out, splattering the floor with come.

They stared at each other for a long moment before Snape spoke. "The effects of the potion will wear off soon. Take your things and go."

Neville hurried to dress while Snape adjusted his own robes and cleaned Neville's work station. Neville thought for sure Snape had preserved a sample of his draught, likely to try to figure out just what he did to it.

Before he reached the door, Neville felt a prickle of awareness and turned around. Snape was pointing his wand at Neville, likely with 'Obliviate' on his lips.

"There's no need, Professor," Neville raised his chin. Even if Snape _had_ done something to the instructions, Neville wanted to keep the memory no matter what. "It was _entirely_ my fault. There was nothing you could do."

Snape nodded, smirk playing about his lips, and sat down at his desk, the dismissal evident.

"Professor?"

"Yes?"

"What mark will I receive on my potion?"

Snape looked up, eyes glittering. "I believe that merits Outstanding."


End file.
